Targeting tumor cells with chemotherapeutic agents conjugated to matriptase antibodies

ABSTRACT

The present invention relates to matriptase antibodies and immunoconjugates of matriptase antibodies with cytotoxic agents and the use thereof for killing or inhibiting the growth of matriptase-expressing cancer cells, such as those of multiple myeloma and breast cancers. In particular, immunoconjugates comprising a matriptase monoclonal antibody and anticancer agents such as doxorubicin (DOX) are introduced, which are equipotent to anticancer agents used in free form but exhibit significantly reduced cardiotoxicity and almost no adverse effects on normal bone marrow-derived mesenchymal stromal cells that do not express matriptase. The present invention also provides compositions comprising these new immunoconjugates and use of them for treatment of malignancies comprising cells that express matriptase. In addition, administration of a matriptase antibody or immunoconjugates of a matriptase antibody and a cytotoxic agent in combination with administration of an immunomodulatory agent, such as thalidomide or an analog thereof, provides a more effective treatment of these cancers.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. Nos. 61/262,373, filed on Nov. 18, 2009, and 61/293,030, filed on Jan. 7, 2010, both of which are hereby incorporated by reference in their entirety for all purposes.

FIELD OF THE INVENTION

The present invention relates to new immunoconjugates comprising an anticancer agent and a monoclonal antibody and use of such immunoconjugates for killing or inhibiting the growth of matriptase expressing cancer cells, including but not limited to those of multiple myeloma and breast cancers. Thus, the present invention also relates to new methods of treating matriptase expressing cancers.

BACKGROUND OF THE INVENTION

Matriptase is a type II transmembrane serine protease expressed by cells of epithelial origin, including breast and prostate tumor cells. Matriptase is characterized by an N-terminal transmembrane domain and multiple extracellular domains, in addition to the conserved extracellular domain (Lin C. Y., et al., J. Biol. Chem., 1999, 274(26):18237-18242). Matriptase is a zymogen that needs to be activated by proteolytic cleavage to become a two-chain active enzyme. Under normal physiological conditions, there is excessive amount of endogenous inhibitor called HGF activator inhibitor-I (HAI-1) that binds to matriptase, tightly regulating the protease activity (Lin, C. Y., et al., J. Biol. Chem., 1999, 274:18231-18236; Oberst, M. D., et al., J. Biol. Chem., 2003, 278:26773-26779). Besides exerting an inhibitory function, HAI-1 also plays a critical role in activation, proper expression and intracellular trafficking of matriptase (Oberst, M. D., et al., J. Biol. Chem., 2003, 278: 26773-26779; Oberst, M. D., et al., Am. J. Physiol. Cell Physiol., 2005, 289:C462-C470).

Matriptase is known to proteolytically activate the hepatocyte growth factor (HGF) and the urokinase plasminogen activator (uPA) and protease-activated receptor in vitro (Lee, S. L., et al., J. Biol. Chem., 2000, 275:36720-36725; Suzuki, M., et al., J. Biol. Chem., 2004, 279:14899-14908). Both HGF and uPA have been implicated for their roles in cellular invasion and metastasis and in cellular motility (Trusolino, L. and Comoglio, P. M., Nat. Rev. Cancer, 2002, 2:289-300; Sidenius, N. and Blasi, F., Cancer Metastasis Rev., 2003, 22:205-222). The cognate receptor for HGF is Met, a receptor tyrosine kinase. Upon the binding of HGF, Met can trigger multiple signaling pathways, including Ras-MAPK, PI3K, Src and Stat3, which eventually leads to invasive growth. High levels of Met combined with overexpression of matriptase are associated with a poor outcome for patients with breast cancer.

Studies of matriptase levels in several solid epithelial-derived tumors including breast, prostate and ovarian carcinomas have been performed in the past few years (for a review, see Uhland, K., Cell. Mol. Life Sci., 2007, 63(24):2968-78). A tissue microarray from patients with breast carcinoma showed that high-level expression of Met, matriptase and HAI-1 are associated with poor patient outcome (Kang, J. Y., et al., Cancer Res., 2003, 63:1101-1105). In prostate tumors, increased levels of matriptase with decreased expression of HAI-1 were associated with increasing tumor grade (Saleem, M., et al., Cancer Epidemiol. Biomarkers Prev., 2006: 15, 217-227). Overexpression of matriptase was also found in 82% of stage I/II and in 55% stage III/VI of patients with ovarian cancer.

Given the significant roles of matriptase in tumor initiation, progression and metastases, several inhibitors for this protease have been investigated in animal models for their anticancer activity. Reduced tumor growth and metastasis formation by matriptase inhibitor, ecotin, has been shown in a PC-3 prostate carcinoma xenograft model (Takeuchi, N., et al., Proc. Natl. Acad. Sci. USA, 1999, 96, 11054-11061). CVS-3983, another matriptase inhibitor, also reduced tumor size in a mouse model of androgen-independent prostate cancer (Galkin, A. V., et al., Prostate, 2004, 61, 228-235).

Doxorubicin (DOX) is one of the most potent anticancer drugs known, but it causes short term toxicity (marrow suppression) and long term cardiotoxicity. Pegylated liposome-encapsulated Dox (Doxil) has recently been approved for the treatment of ovarian cancer and multiple myeloma, and has been shown to be less cardiotoxic than DOX. However, it can cause palmar-plantar erythrodysesthesia, also called hand-foot syndrome. Due to these limitations, attempts have been made to design targeted delivery for DOX by conjugating this drug with a monoclonal antibody (mAb) that recognizes an antigen expressed on the surface of cancer cells. For example, an immunoconjugate between CD-74 antibody and doxorubicin (DOX) is now in the phase I/II clinical trial for treatment of multiple myeloma.

Although survival of patients with multiple myeloma (MM) has been significantly improved owing to the advances in new therapeutics for the patients in the past decade, nevertheless, the disease remains incurable. New or improved therapeutic agents are therefore urgently needed.

SUMMARY OF THE INVENTION

The present invention provides new therapeutic agents for the treatment of hematologic cancers such as MM to meet the foregoing need. Matriptase, a membrane-bound serine type II protease, is expressed in cell lines of multiple myeloma (MM) and other hematologic cancer cells. The present invention provides a matriptase antibody conjugated to a cytotoxic agent, for example, doxorubicin, for selectively targeting matriptase expressing cells. Antibodies conjugated with potent anticancer drugs to target matriptase-expressing cancer cells have various advantages. For example, the selective delivery of the chemotherapeutic agent to tumor cells overexpressing matriptase results in less toxicity toward the normal tissues. Moreover, since levels of matriptase mRNA have been found in tumors in other organs, including kidney, lung, colon, bladder, pancreas, prostate, skin, breast, thyroid and ovary, these immunoconjugates are useful for treating these cancers.

In one embodiment, the present invention provides an immunoconjugate of a matriptase antibody and DOX. This immunoconjugate is equipotent to free doxorubicin against growth of MM cells. Normal bone marrow-derived mesenchymal stromal cells that do not express matriptase and for which DOX is cytotoxic are insensitive to the immunoconjugate. Further, a lack of expression of matriptase in cardiomyocytes indicates that this novel immunoconjugate of doxorubicin lacks cardiotoxicity, a serious side effect of large cumulative doses of this drug. Targeting matriptase expressed on myeloma cells with an antibody carrying DOX increases the effectiveness and therapeutic index of DOX and improves the treatment of patients with multiple myeloma.

The invention disclosed herein also encompasses conjugates of other appropriate anticancer agents with matriptase antibodies and use of these conjugates for treatment of other cancers in which the cells express matriptase. For example, the immunoconjugates can also be used for any matriptase-positive malignant B cell lymphoma including Burkitt's lymphoma and diffuse large B-cell lymphoma. Moreover, the immunoconjugates of the present invention in which the cytotoxic agent is DOX are a particularly effective treatment for epithelial carcinomas expressing matriptase such as prostate and breast tumors, since DOX is used to treat these malignancies. The immunoconjugates are also an effective treatment for cancers refractory to doxorubicin due to different uptake mechanisms of these two drugs.

Further, it has been discovered in accordance with the present invention that thalidomide, an immunomodulatory agent, markedly induces activation of matriptase in myeloma cells. Thus, the present invention provides for administration of immunoconjugates targeting active matriptase in combination with administration of immunomodulatory agents, including but not limited to thalidomide and its analogs, for the treatment of MM and other cancers. Thalidomide analogs are known in the art and include, for example, lenalidomide, CC-3052, CC-4047, CC-5103, IMiD3, EM12, and ENMD0995.

Thus, in one aspect the present invention provides a method of treating a hematological malignancy, comprising administering to a subject in need of such a treatment a composition comprising a therapeutically effective amount of a matriptase antibody. In another aspect the present invention provides a method of treating a hematological malignancy, the method comprising administering to a subject in need of such a treatment a therapeutically effective amount of a composition comprising a matriptase antibody in combination with a therapeutically effective amount of an immunomodulatory agent that activates matriptase.

In another aspect the present invention provides a method of treating a malignancy comprising cells that express matriptase, the method comprising administering to a subject in need of such a treatment a therapeutically effective amount of a composition comprising an immunoconjugate between a matriptase antibody and a cytotoxic agent.

In another aspect the present invention provides a method of treating a malignancy comprising cells that express matriptase, the method comprising administering to a subject in need of such a treatment a therapeutically effective amount of a composition comprising an immunoconjugate between a matriptase antibody and a cytotoxic agent in combination with a therapeutically effective amount of an immunomodulatory agent that activates matriptase.

In another aspect the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, comprising a matriptase antibody and a cytotoxic agent.

In another aspect the present invention provides a composition comprising an immunoconjugate selectively targeting cancer cells that express matriptase according to any of the embodiments described above in the fifth aspect.

In another aspect the present invention provides a method of diagnosing a hematological malignancy comprising contacting a test sample containing hematological cells from a mammal with a matriptase antibody and detecting the formation of a complex between the antibody and matriptase, wherein formation of a complex is indicative of a malignancy.

In another aspect the present invention provides a method of inhibiting the growth of a hematopoietic cell that expresses matriptase, the method comprising treating the hematopoietic cell with a matriptase antibody or an immunoconjugate according to any of the embodiments described above.

In another aspect the present invention provides an assay kit for detecting expression of matriptase in mammalian tissues or cells, comprising an immunoconjugate according to any of the embodiments described above.

In another aspect the present invention provides a kit for treatment of a malignancy comprising cells that express matriptase, the kit comprising an immunoconjugate according to any of the embodiments described above.

In another aspect the present invention provides use of an immunoconjugate according to any of the embodiments described above for treatment of a malignancy comprising cells that express matriptase.

In another aspect the present invention provides use of an immunoconjugate according to any of the embodiments described above for manufacture of a medicament for treatment of a malignancy comprising cells that express matriptase.

These and other aspects of the present invention will be better appreciated by reference to the following drawings and detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B, 1C and 1D represent Western analyses of matriptase and HAI-1 in human lymphoma and myeloma cells. The cell lines in panel (A) include Hs 445 (lane 2), HuT 78 (lane 3), Farage (lane 4), Raji (lane 5), Daudi (lane 6), Namalwa (lane 7), Ramos (lane 8), ST486 (lane 9), SU-DHL-4 (lane 10), SU-DHL-6 (lane 11), OCI-LY-3 (lane 12), RPMI-8226 (lane 13). The cell lines in panel (B) include HL-60 (lane 2), Reh (lane 3), Jurkat (lane 4), SUP-T1 (lane 5), CCRF-CEM (lane 6), CCRF-HSB-2 (lane 7), MOLT-3 (lane 8), MOLT-4 (lane 9), CCRF-SB (lane 10), RS4-11 (lane 11), THP-1 (lane 12), U937 (lane 13). Panel (C) shows the assessment of levels of matriptase in three MM cell lines as indicated. GAPDH served as an internal control. Panel (D) shows the tissue sections of paraffin-embedded multiple myeloma stained with the matriptase mAb M24, the HAI-1mAb M19, and the activated matriptase M69, respectively as indicated.

FIG. 2 illustrates cytotoxic effects of M24-DOX on MM cells. MM cells (1×105/well) in 24-well plates were treated with or without M24-DOX at varying concentration for 48 hours. Cell number was counted by Vi-Cell counter (Beckman). Error bars represent SEM. Statistical comparisons: *, significantly lower than control, p<0.036. Plotted values represent duplicates from three separate experiments.

FIGS. 3A and 3B represent internalization of M24-DOX within cells. Following exposure of MM.1S cells to M24-DOX for varying periods of time, and the cells were fixed and stained. The immunoconjugate was visualized by fluorescent microscopy. DAPI was used for nuclear staining.

FIGS. 4A, 4B, and 4C illustrate reduced cytotoxicity of M24-DOX to normal marrow mesenchymal cells. Bone marrow-derived mesenchymal stromal cells (5×104/well, 24-well plates) were treated with M24-DOX or free DOX at varying concentrations for 4 days. Cell numbers were determined by Vi-Cell counter. (A) shows that M24-DOX lacks cytotoxicity to stromal cells; (B) shows reduced cytotoxicity to cardiomyocytes; and (C) shows comparison of M24-DOX with DOX and control.

FIG. 5 illustrates activation of matriptase in MM cells induced by thalidomide. MM cells (MM.1S) were treated with varying concentrations of thalidomide as indicated for 24 hours followed by Western analyses to detect the activation of matriptase using a specific monoclonal antibody (M69) to the active form of the enzyme. The latent form of the protease was also detected using a mAb (M24) to the inactive form enzyme. GAPDH served as control.

FIGS. 6A and 6B illustrate that thalidomide sensitizes MM cells to M69-DOX, but not M24-DOX: (A) comparison of treatment of MM cells by M69-DOX alone with the M69-DOX/thalidomide combination treatment; and (B) comparison of treatment of MM cells by M24-DOX alone with the M24-DOX/thalidomide combination treatment.

FIG. 7 illustrates activation of matriptase in MM cells induced by thalidomide. MM cells (MM.1S) were treated with varying concentrations of thalidomide as indicated for 24 hours followed by Western analyses to detect the activation of matriptase using a specific monoclonal antibody (M69) to the active form of the enzyme. The latent form of the protease was also detected using a mAb (M24) to the inactive form enzyme. GAPDH served as control.

FIG. 8 illustrates the M69-DOX conjugate targeting active matriptase inhibited breast tumor growth in vivo, comparing treatment by M69-DOX at 10 mg/Kg and 20 mg/Kg doses with treatment by DOX at 2 mg/Kg dose and the control.

FIG. 9 illustrates reduction of the tumor weight by M69-DOX at 10 mg/Kg and 20 mg/Kg doses in comparison with treatment by DOX at 2 mg/Kg dose and the control.

FIG. 10 illustrates the average weights of the mice during the treatment by M69-DOX at 20 mg/Kg and 2 mg/Kg doses or DOX at 2 mg/Kg dose in comparison with the control.

DETAILED DESCRIPTION OF THE INVENTION

While matriptase is mainly produced by normal epithelial and a variety of epithelial-derived carcinoma cells, it has been discovered in accordance with the present invention that this membrane-bound protease is also present in various cells of hematological malignancies. The present invention provides methods of treating hematological malignancies by administering antibodies to matriptase. The invention further provides immunoconjugates of a matriptase antibody and a cytotoxic agent, and methods of using the immunoconjugates for treatment of malignancies in which sells express matriptase. In one preferred embodiment of this invention, DOX is conjugated with a monoclonal antibody to matriptase for targeting myeloma cells. These novel immunoconjugates effectively block proliferation of MM cells while having a remarkable advantage, inter alia, of a selective toxicity toward cells expressing the target marker. Significantly, bone marrow-derived mesenchymal stromal cells that do not express matriptase were found to be insensitive to the immunoconjugates, whereas free DOX showed cytotoxicity in such cells.

Thus, in a first aspect the present invention provides a method of treating a hematological malignancy, comprising administering to a subject in need of such a treatment a composition comprising a therapeutically effective amount of a matriptase antibody.

In one embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the hematological malignancy is a cancer comprising cells that express matriptase.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the hematological malignancy is selected from the group consisting of leukemias, lymphomas, and myelomas.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the hematological malignancy is selected from the group consisting of acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), chronic myelogenous leukemia (CML), acute monocytic leukemia (AMOL)), Hodgkin's lymphomas, Non-Hodgkin's lymphomas, Burkitt's lymphoma (BL), diffuse large B-cell lymphoma (DLBL), Mantle cell lymphoma (MCL), and multiple myeloma.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the hematological malignancy is multiple myeloma.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the hematological malignancy is a cancer comprising cells that express matriptase.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the matriptase antibody is a monoclonal antibody (mAb).

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the matriptase antibody is selected from the group consisting of chimeric antibodies, humanized antibodies, and human antibodies.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the composition further comprises a pharmaceutically acceptable carrier.

In a second aspect the present invention provides a method of treating a hematological malignancy, the method comprising administering to a subject in need of such a treatment a therapeutically effective amount of a composition comprising a matriptase antibody in combination with a therapeutically effective amount of an immunomodulatory agent that activates matriptase.

In one embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the malignancy is multiple myeloma.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the matriptase antibody is an antibody specific for activated matriptase.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the matriptase antibody is a mAb M69.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the matriptase antibody is an antigen-binding fragment.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the matriptase antibody is selected from the group consisting of chimeric antibodies, humanized antibodies, and human antibodies.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the matriptase antibody is a monoclonal antibody, and the immunomodulatory agent is thalidomide or a thalidomide analog.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the immunomodulatory agent is administered to the subject for a sufficient amount of time so that matriptase is activated prior to administration of the composition comprising the matriptase antibody.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein the composition further comprises a pharmaceutically acceptable carrier.

In a third aspect the present invention provides a method of treating a malignancy comprising cells that express matriptase, the method comprising administering to a subject in need of such a treatment a therapeutically effective amount of a composition comprising an immunoconjugate between a matriptase antibody and a cytotoxic agent.

In one embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the hematological malignancy is a cancer comprising cells that express matriptase.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is a cancer.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is a matriptase-positive malignant B cell lymphoma or an epithelial carcinoma.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is a matriptase-positive malignant B cell lymphoma selected from the group consisting of Mantle cell lymphoma (MCL), Burkitt's lymphoma (BL), and diffuse large B-cell lymphoma (DLBL).

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is an epithelial carcinoma selected from the group consisting of prostate, breast, brain, kidney, lung, colon, bladder, and ovary as well as other tumor types, including thyroid tumor, skin tumor, and mesothelioma.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is selected from the group consisting of acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), chronic myelogenous leukemia (CML), acute monocytic leukemia (AMOL), Hodgkin's lymphomas, Non-Hodgkin's lymphomas, Mantle cell lymphoma (MCL) and multiple myeloma.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is multiple myeloma.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is a monoclonal antibody (mAb).

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is an antigen-binding fragment.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is selected from the group consisting of chimeric antibodies, humanized antibodies, and human antibodies.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the cytotoxic agent is selected from toxins, antibiotics, and compounds comprising radioactive isotopes.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the cytotoxic agent is selected from doxorubicin (DOX), auristatin, calicheamicin, and ricin.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the cytotoxic agent is doxorubicin (DOX).

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is a cancer refractory to the treatment of doxorubicin.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the immunoconjugate is M24-DOX or M69-DOX.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the cytotoxic agent is coupled to the matriptase antibody through a covalent bond.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the subject is a mammalian patient.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the subject is a human.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the composition further comprises a pharmaceutically acceptable carrier.

In a fourth aspect the present invention provides a method of treating a malignancy comprising cells that express matriptase, the method comprising administering to a subject in need of such a treatment a therapeutically effective amount of a composition comprising an immunoconjugate between a matriptase antibody and a cytotoxic agent in combination with a therapeutically effective amount of an immunomodulatory agent that activates matriptase.

In one embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the malignancy is multiple myeloma.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is an antibody specific for activated matriptase.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is a monoclonal antibody (mAb).

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is an antigen-binding fragment.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is selected from the group consisting of chimeric antibodies, humanized antibodies, and human antibodies.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the matriptase antibody is mAb M69, and the cytotoxic agent is doxorubicin (DOX).

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the immunomodulatory agent is thalidomide or a thalidomide analog.

In another embodiment of this aspect, the present invention provides a method of treating a malignancy comprising cells that express matriptase, wherein the immunomodulatory agent is administered to the subject for a sufficient amount of time so that matriptase is activated prior to administration of the composition comprising the immunoconjugate.

In another embodiment of this aspect, the present invention provides a method of treating a hematological malignancy, wherein: (a) the malignancy is multiple myeloma; (b) the immunoconjugate comprises a matriptase antibody and DOX; and (c) the immunomodulatory agent is thalidomide or a thalidomide analog.

In a fifth aspect the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, comprising a matriptase antibody and a cytotoxic agent.

In one embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein the matriptase antibody recognizes an antigen expressed on the surface of the cancer cells.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein the matriptase antibody is a monoclonal antibody (mAb).

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein the matriptase antibody is an antigen-binding fragment.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein the matriptase antibody is selected from the group consisting of chimeric antibodies, humanized antibodies, and human antibodies.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein the matriptase antibody is a monoclonal antibody, and the cytotoxic agent is selected from the group consisting of doxorubicin (DOX), auristatin, calicheamicin, and ricin.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein the conjugate is formed through a covalent bond between the matriptase antibody and the DOX moiety

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein one molecule of the matriptase antibody is coupled with up to 15 molecules of DOX.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein one molecule of the matriptase antibody is coupled with about 5-10 molecules of DOX.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, wherein one molecule of the matriptase antibody is coupled about 7 molecules of DOX.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, the immunoconjugate having reduced or no cardiotoxicity in comparison with the cytotoxic agent when administered in the absence of the matriptase antibody.

In another embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, the immunoconjugate having minimized or no adverse effects on bone marrow-derived mesenchymal stromal cells which do not express matriptase.

In another aspect the present invention provides a composition comprising an immunoconjugate selectively targeting cancer cells that express matriptase according to any of the embodiments described above in the fifth aspect.

In one embodiment of this aspect, the present invention provides an immunoconjugate selectively targeting cancer cells that express matriptase, further comprising a pharmaceutically acceptable carrier.

In another aspect the present invention provides a method of diagnosing a hematological malignancy comprising contacting a test sample containing hematological cells from a mammal with a matriptase antibody and detecting the formation of a complex between the antibody and matriptase, wherein formation of a complex is indicative of a malignancy.

In another aspect the present invention provides a method of inhibiting the growth of a hematopoietic cell that expresses matriptase, the method comprising treating the hematopoietic cell with a matriptase antibody or an immunoconjugate according to any of the embodiments described above.

In another aspect the present invention provides an assay kit for detecting expression of matriptase in mammalian tissues or cells, comprising an immunoconjugate according to any of the embodiments described above.

In another aspect the present invention provides a kit for treatment of a malignancy comprising cells that express matriptase, the kit comprising an immunoconjugate according to any of the embodiments described above.

In another aspect the present invention provides use of an immunoconjugate according to any of the embodiments described above for treatment of a malignancy comprising cells that express matriptase.

In another aspect the present invention provides use of an immunoconjugate according to any of the embodiments described above for manufacture of a medicament for treatment of a malignancy comprising cells that express matriptase.

DEFINITIONS

As used herein, the term “biological sample” refers to a specimen comprising body fluids, cells or tissue from a subject, preferably a human subject. The sample can also be body fluid that has come into contact, either naturally or by artificial methods (e.g. surgical means), with a malignant cell or cells of a pre-malignant lesion.

As used herein, the term “expression of matriptase,” or the like, refers to any biological sample comprising one or more cells which express a form or forms of matriptase.

As used herein, the term “subject” refers to an animal, preferably mammalian, and most preferably human.

As used herein, the term “antibody” refers to complete, intact antibodies, and Fab fragments and F(ab), fragments thereof. Complete, intact antibodies include monoclonal antibodies such as murine monoclonal antibodies (mAb), chimeric antibodies, humanized antibodies, and human antibodies.

An “antibody fragment” can be prepared by known methods, for example, as disclosed by Goldenberg, U.S. Pat. Nos. 4,036,945 and 4,331,647 and references contained therein. Another form of an antibody fragment is a peptide coding for a single complementarity-determining region (CDR). A CDR is a segment of the variable region of an antibody that is complementary in structure to the epitope to which the antibody binds and is more variable than the rest of the variable region. CDR peptides can be obtained by constructing genes encoding the CDR of an antibody of interest. Such genes are prepared, for example, by using the polymerase chain reaction to synthesize the variable region from RNA of antibody-producing cells.

As used herein, the term “immunoconjugate” refers to a conjugate of an antibody component with a molecule or a therapeutic or diagnostic agent. The therapeutic or diagnostic agent can comprise a radioactive or non-radioactive label. The antibodies that used to prepare immunoconjugates include, but is not limited to, monoclonal antibodies, chimeric antibodies, humanized antibodies, and human antibodies. Here a preferred immunoconjugate is a conjugate between a matriptase monoclonal antibody and a cytotoxic agent, and a more preferred immunoconjugate is one comprising a matriptase monoclonal antibody and a FDA-approved anticancer agent, including but not limited to doxorubicin (DOX), auristatin, calicheamicin, or ricin.

As used herein, the term “cytotoxic agent” refers to a substance that inhibits or prevents the function of cells and/or causes destruction of cells. The term is intended to include chemotherapeutic agents, such as methotrexate, adriamicin, vinca alkaloids (vincristine, vinblastine, etoposide), doxorubicin, melphalan, mitomycin C, chlorambucil, daunorubicin or other intercalating agents, enzymes and fragments thereof such as nucleolytic enzymes, antibiotics, and toxins such as small molecule toxins or enzymatically active toxins of bacterial, fungal, plant or animal origin, including fragments and/or variants thereof, and the various antitumor or anticancer agents disclosed below. The term also encompasses compounds comprising one or more radioactive isotopes (e.g., At²¹¹, I¹³¹, I¹²⁵, Y⁹⁰, Re¹⁸⁶, Re¹⁸⁸, sm¹⁵³, Bi²¹², P³², as well as radioactive isotopes of Lu).

As used herein, the term “doxorubicin” (or “DOX”) refers to an anthracycline antibiotic with a systematic (IUPAC) chemical name of (8S,10S)-10-(4-amino-5-hydroxy-6-methyl-tetrahydro-2H-pyran-2-yloxy)-6,8,11-trihydroxy-8-(2-hydroxyacetyl)-1-methoxy-7,8,9,10-tetrahydrotetracene-5,12-dione.

As used herein, the term “carrier” refers to a molecule or higher-ordered structure that is capable of associating with a therapeutic or diagnostic agent to facilitate delivery of the agent to a targeted cell. Carriers may include molecules such as lipids or polymers, such as amphiphilic lipids or carbohydrates, or higher-ordered structures, such as micelles, liposomes, and nanoparticles.

The immunoconjugates or compositions disclosed herein can be formulated according to known methods and may include one or more pharmaceutically suitable excipients, one or more additional ingredients, or combinations thereof.

The immunoconjugates or compositions disclosed herein can be formulated for intravenous administration via, for example, bolus injection or continuous infusion. Formulations for injection can be presented in unit dosage form, e.g., in ampules or in multi-dose containers, with an added preservative. The compositions can take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and can contain formulatory agents such as suspending, stabilizing and/or dispersing agents. Alternatively, the active ingredient can be in powder form for constitution with a suitable vehicle, e.g., sterile pyrogen-free water, before use.

The immunoconjugate or compositions may also be administered to a mammal subcutaneously or even by other parenteral routes. Moreover, the administration may be by continuous infusion or by single or multiple boluses. In general, the dosage of an administered immunoconjugate will vary depending upon such factors as the patient's age, weight, height, sex, general medical condition and previous medical history.

Additional pharmaceutical methods may be employed to control the duration of action of the therapeutic or diagnostic conjugate or naked antibody. Control release preparations can be prepared through the use of polymers to complex or adsorb the immunoconjugate or naked antibody.

An antibody preparation is said to be administered in a “therapeutically effective amount” if the amount administered is physiologically significant. An agent is physiologically significant if its presence results in a detectable change in the physiology of a recipient mammal, including a reduction in the number of cancer cells, a reduction in the size of a tumor, or an inhibition in the growth of a tumor. In particular, an antibody preparation is physiologically significant if its presence invokes an antitumor response or mitigates the signs and symptoms of an autoimmune disease state. A physiologically significant effect could also be the evocation of a humoral and/or cellular immune response in the recipient mammal.

It will be appreciated that actual preferred amounts of a pharmaceutical composition used in a given therapy will vary depending upon the particular form being utilized, the particular compositions formulated, the mode of application the particular site of administration, the patient's weight, general health, sex, etc., the particular indication being treated, etc. and other such factors that are recognized by those skilled in the art including the attendant physician or veterinarian. Optimal administration rates for a given protocol of administration can be readily determined by those skilled in the art using conventional dosage determination tests.

Preparation of Immunoconjugates

The immunoconjugates described herein can be prepared by known methods of linking antibodies with lipids, carbohydrates, protein, or other molecules. For example, the binding molecules described herein can be conjugated with one or more of the carriers described herein (e.g., lipids, polymers, liposomes, micelles, or nanoparticles) to form an immunoconjugate, and the immunoconjugate can incorporate a therapeutic or diagnostic agent either covalently, non-covalently, or otherwise. Further, any of the binding molecules described herein can be further conjugated with one or more therapeutic or diagnostic agents described herein, or additional carriers. Generally, one therapeutic or diagnostic agent may be attached to each binding molecule but more than one therapeutic agent or diagnostic agent can be attached to the same binding molecule. Further, the therapeutic agents do not need to be the same but can be different therapeutic agents.

For example, to synthesize an immunoconjugate of an antibody and DOX, DOX may be first reacted with succinimidyl 4-[N-maleimidomethyl]cyclohexane-1-carboxylate (SMCC), and the antibody against matriptase may be reacted with N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), followed by coupling of these two intermediates.

Methods of Treatment

The present invention encompasses use of the matriptase antibodies or immunoconjugates or compositions comprising the matriptase antibodies or immunoconjugates as the primary composition for treatment of a malignancy comprising cells that express matriptase. The malignancy includes, but is not limited to, solid tumor, non-Hodgkin's lymphoma, Hodgkin's lymphoma, multiple myeloma, a B-cell malignancy and/or a T-cell malignancy. The solid tumor is selected from the group consisting of a melanoma, carcinoma and sarcoma and the carcinoma is selected from the group consisting of a renal carcinoma, lung carcinoma, intestinal carcinoma, stomach carcinoma and melanoma. The B-cell malignancy is selected from the group consisting of indolent forms of B-cell lymphomas, aggressive forms of B-cell lymphomas, chronic lymphatic leukemias, acute lymphatic leukemias, and multiple myeloma, B-cell disorders and other diseases. In particular, the compositions described herein are particularly useful for treatment of various autoimmune as well as indolent forms of B-cell lymphomas, aggressive forms of B-cell lymphomas, chronic lymphatic leukemias, acute lymphatic leukemias, multiple myeloma, and Waldenstrom's macroglobulinemia. The methods of treatment comprise administering to a mammal in need of such treatment a therapeutically effective amount of a composition comprising the antibody or immunoconjugate.

Antibodies

Antibodies against matriptase can be made by methods known in the art and disclosed, for example, by Lin C. Y., et al., J. Biol. Chem., 1999, 274 (26):18237-18242. Antibodies against matriptase include antibodies that are specific for latent matriptase, antibodies that are specific for activated matriptase, and antibodies that recognize both latent and activated matriptase.

The antibodies and immunogenic portions thereof of this invention are administered at a concentration that is therapeutically effective to prevent or treat any of the aforementioned disease states. To accomplish this goal, the antibodies may be formulated using a variety of acceptable excipients known in the art. Typically, the antibodies are preferably administered by injection, either intravenously or intraperitoneally. Methods to accomplish this administration are known to those of ordinary skill in the art. The compositions may also be topically or orally administered, or be capable of transmission across mucous membranes.

Before administration to patients, formulants may be added to the antibodies. A liquid formulation is preferred. For example, these formulants may include oils, polymers, vitamins, carbohydrates, amino acids, salts, buffers, albumin, surfactants, or bulking agents. Preferably carbohydrates include sugar or sugar alcohols, such as mono-, di- or polysaccharides, or water soluble glucans. The saccharides or glucans can include fructose, dextrose, lactose, glucose, mannose, sorbose, xylose, maltose, sucrose, dextran, pullulan, dextrain, alpha- and beta-cyclodextrin, soluble starch, hydroxyethyl starch and carboxymethylcellulose, or mixtures thereof.

Additionally, antibodies can be chemically modified by covalent conjugation to a polymer to increase their circulating half-life. Preferred polymers, and methods to attach them to peptides, are shown in U.S. Pat. Nos. 4,766,106; 4,179,337; 4,495,285; and 4,609,546. Preferred polymers are polyoxyethylated polyols and polyethylene glycol (PEG).

Water soluble polyoxyethylated polyols are also useful in the present invention. They include polyoxyethylated sorbitol, polyoxyethylated glucose, polyoxyethylated glycerol (POG), etc.

Another drug delivery system for increasing circulatory half-life is the liposome. Methods of preparing liposome delivery systems are discussed in Gabizon et al., Cancer Res. 42: 4734-9 (1982); Szoka et al., Annu. Rev. Biophys. Bioeng. 9: 467-508 (1980); Szoka et al., Meth. Enzymol. 149: 143-7 (1987); and Langne et al., Pol. J. Pharmacol. 51: 211-22 (1999). Other drug delivery systems are known in the art.

As stated above, the antibodies and compositions of this invention are used preferably to treat human patients to prevent or treat any of the above-defined disease states. The preferred route of administration is parenteral. In parenteral administration, the compositions of this invention will be formulated in a unit dosage injectable form such as a solution, suspension or emulsion, in association with a pharmaceutically acceptable parenteral vehicle. Such vehicles are inherently nontoxic and non-therapeutic. Examples of such vehicles are saline, Ringer's solution, dextrose solution, and Hanks' solution. Non-aqueous vehicles such as fixed oils and ethyl oleate may also be used.

The matriptase mAb-Dox conjugate disclosed herein represents an example for developing anticancer agents specifically targeting cancer cells. Matriptase mAbs can be linked to other types of cytotoxic agent such as anti-tubulin compounds that would work better with certain types of tumors, or can be coupled to lyposomal or nanoparticles for targeted delivery of any types of agents, including peptides, shRNA/siRNA and very toxic compounds of little potential in cancer treatment due to severe side effects.

The following non-limiting examples further illustrate certain aspects of the invention.

EXAMPLES Example 1 Expression of Matriptase in Multiple Myeloma and B-Cell Lymphoma Cells

A panel of 24 cell lines of human hematopoietic malignancies was analyzed by Western blotting for matriptase as well as its endogenous inhibitor HGF activator inhibitor-1 or HAI-1 (FIG. 1). Cell lysates were prepared from 24 hematopoietic cancer cells (lanes 2-14) and T-47D breast cancer cells (lane 1). Equal amounts of proteins were resolved by SDS-PAGE. Levels of matriptase and HAI-1 were assessed by immunoblot analyses using an anti-matriptase mAb and anti-HAI-1 mAb as indicated (FIGS. 1A and 1B).

Matriptase was expressed in the majority of the B-cell lymphomas as well as in multiple myeloma cells, indicating that the protease is an important marker for these cancers. In contrast, HAI-1 levels in lymphoma and myeloma appear to be much lower than those in carcinomas, and HAI-1 expression is often lost in highly aggressive lymphomas (Table 1).

To further verify the expression of matriptase in multiple myeloma cells, six cases of paraffin-embedded MM specimens were examined Matriptase was positive in four cases, among which two were HAI-1 positive and the other two were negative (FIG. 1D).

The levels of matriptase in cell lines of multiple myeloma were assessed (FIG. 1C). All three MM cells produced the protease.

Example 2 Preparation of DOX-Immunoconjugate

Monoclonal antibodies against matriptase (M24 or M69, obtained from C Y Lin, University of Maryland, Baltimore, Md.; Lin C. Y., et al., J. Biol. Chem., 1999, 274 (26):18237-18242; Chen, Y. W., et al. J. Biol. Chem., 2010, 285 (41):31755-31762) was conjugated to DOX (Sigma) by using Protein-Protein Coupling kit (Invitrogen) according to the manufacture's instruction with some minor modification. Briefly, DOX was reacted with crosslinker SMCC (succinimidyl-4-(N-maleimidomethyl)cyclohexane-1-carboxylate) at a molar ratio (MR) between 1:3 and 1:1.5 (DOX:SMCC) for 1 hour at room temperature with constant stirring. About 200 mg M24 mAb was reacted with SPDP (Succinimidyl 3-(2-pyridyldithio)-propionate) for 1 hour at room temperature followed by exchange of phosphate buffer using Centrifugal Filter Device (Ultrafree, Millipore). Alternatively, the mAb can be separated from free SPDP by gel filtration with Sephadex G50. DOX maleimide derivative was then conjugated to thiolated M24 or M69 mAb for 3 hours at room temperature followed by dialysis in the phosphate buffer to remove the free DOX. Gel filtration with Sephadex G50 can also used to remove the uncoupled DOX if the scale of preparation is larger than one (1) gram of proteins. The molar ratio of protein to DOX is determined through measuring DOX by fluorescence and protein concentration.

Since DOX emits fluorescence by UV excitation, the coupling of DOX to the antibody was measured, based on the fluorescence generated by the immunoconjugate. M24-DOX at 1 μg/ml approximately has the same intensity of fluorescence as that of DOX at 25 nM. Hence, 1 molecule of the mAB is coupled with nearly 7 molecules of DOX.

TABLE 1 Summary of matriptase and HAI-1 expression in human lymphoma and leukemia cells Disease/ HAI- Cell line Cell Type Source Viruses* Matriptase 1 HL-60 Promyeloblast AML − − +/− Reh Lymphoblast ALL − − +++ Jurkat T-Lymphoblast ALL − − + SUP-T1 T-Lymphoblast LL − +++ − CCRF-CEM T-Lymphoblast ALL − − +/− CCRF-HSB-2 T-Lymphoblast ALL − − ++ MOLT-3 T-Lymphoblast ALL − − − MOLT-4 T-Lymphoblast ALL − − − CCRF-SB B-Lymphoblast ALL EBV+ − +/− RS4;11 B-Lymphoblast ALL − − +/− THP-1 Monocyte Acute − ++ +/− Monocytic Leukemia U-937 Monocyte Histiocytic − − − Lymphoma Hs 445 B-Lymphoblast HL EBV+ − +/− HuT 78 cutaneous T Sezary − − ++ lymphocyte Syndrome Farage B-Lymphoblast EBV- EBV+ +/− − transformed B cell lymphoma RPMI 8226 B-Lymphoblast MM − ++++ + Daudi B-Lymphoblast BL EBV+ ++++ − Namalwa B-Lymphoblast BL EBV+, ++++ − SMRV+ Raji B-Lymphoblast BL EBV+ ++ − Ramos B-Lymphoblast BL − ++++ − ST486 B-Lymphoblast BL − ++++ − SU-DHL-4 B-Lymphoblast DLBL − ++++ +/− SU-DHL-6 B-Lymphoblast DLBL − ++++ +/− OCI-LY-3 B-Lymphoblast DLBL − ++++ +/− Abbreviation: AML, acute myelocytic leukemia; ALL, acute lymphocytic leukemia; BL, Burkitt's lymphoma; DLBL, diffuse large B-cell lymphoma; EBV, Epstein-Barr virus; HL, Hodgkin's lymphoma; LL, lymphoblastic leukemia; MM, multiple myeloma; SMRV, squirrel monkey retrovirus

Example 3 Cytotoxicity of M24-DOX Toward Multiple Myeloma Cells

To assess the cytotoxic effect of the immunoconjugate, MM cells were treated with the conjugated DOX at various concentrations for 48 hours. The immunoconjugate inhibited cell proliferation in a dose-dependent manner. The EC50 of the immunoconjugate was 5 μg/ml (protein). This cytotoxic effect was also observed with treatment of free DOX at 200 nM. As the concentration of M24-DOX at 5 μg/ml is equivalent to 250 nM of free DOX based on the intensity of fluorescence, the potency of the conjugated DOX is therefore similar to the free drug. Exposure of the cells to unmodified antibody had no effect on cell growth, demonstrating that the M24-DOX induced cytotoxic effect is mediated through DOX activity. Two other MM cell lines including OPM-2 and RPMI-8226 were also tested for the cytotoxic activity of M24-DOX as shown in FIG. 2 where MM cells (1×10⁵/well) in 24-well plates were treated with or without M24-DOX at varying concentrations for 48 hours. Cell number was counted by Vi-Cell counter (Beckman).

Both types of cells also responded to the drug in a similar fashion as MM.1S did.

Example 4 Nuclear Localization of M24-DOX

To demonstrate internalization of the immunoconjugate of DOX in MM.1S cells, fluorescent microscopy was used to trace the subcellular localization of M24-DOX after exposure of the cells to the drug for various periods of time. Following exposure of MM.1S cells to M24-DOX for varying periods of time, the cells were fixed and stained. The immunoconjugate was visualized by fluorescent microscopy. DAPI was used for nuclear staining.

Trace amounts of nuclear fluorescence were detected in a small number of cells after 3 min exposure of the M24-DOX. Both the number of fluorescence stained cells and intensity of signal localizing in the nuclei were significantly increased with incubation times longer than 30 min (FIG. 3A). The pictures with higher magnification revealed swelling of nuclei of cells exposed to the drug for 60 min or longer, indicative of typical DOX-induced apoptosis (FIG. 3B). These data indicate that following binding to the antigen, the immunoconjugate was rapidly internalized and significant nuclear localization of DOX was observed after 10 min of treatment.

Example 5 Tolerance of Bone Marrow-Derived Mesenchymal Stem Cells (MSCs) Toward M24-DOX

Human bone marrow-derived MSCs, which lack matriptase expression, were used as a control to determine the cytotoxic selectivity of M24-DOX as shown in FIG. 4 where bone marrow-derived mesenchymal stromal cells (5×10⁴/well, 24-well plates) were treated with M24-DOX or free DOX at varying concentrations for 4 days. Cell numbers were determined by Vi-Cell counter.

The MSCs were insensitive to the immunoconjugate at a concentration as high as 20 μg/ml, whereas free DOX was able to significantly inhibit cell proliferation at 5 nM. Expression of matriptase is mainly restricted to epithelial cells in normal tissues. Absence of this protease in cardiomyocytes indicates that M24-DOX will exhibit significantly reduced cardiotoxicity.

Example 6 Targeting Active Matriptase

DOX was also conjugated with another matriptase mAb (M69) that specifically binds to the active two-chains of the enzyme. While active matriptase levels were found in most breast tumors, the active form of the protease is barely detectable in the normal tissues of the mammary gland (FIG. 5). These data indicate that the DOX-conjugate with M69, referred to as M69-DOX, offers additional selectivity in targeting tumors expressing activated matriptase with regard to toxicity toward normal tissues. As epithelial tissues express matriptase, the toxicity of M24-DOX toward the healthy tissues is a concern. For instance, a previous DOX-conjugate called BR96 targeting Lewis-Y antigen in carcinoma cells failed in the phase II trial due to considerable gastrointestinal (GI) toxicity (Tolcher, A. W., et al., J. Clin. Oncol., 1999, 17: 478-484) In contrast to the expression of latent form of matriptase in epithelial tissues, the level of the active form of this protease is hardly detectable by immunohistochemistry. Hence, M69-DOX is less toxic to epithelia.

Example 7 Enhanced Cytotoxic Effects of M69-DOX by Thalidomide

Thalidomide is a therapeutic for multiple myeloma treatment, and the combination of thalidomide and dexamethasone is one of the most common regimens for treatment of patients with multiple myeloma, with an response rate of up to 60-70% (Denz, U., Eur. J. Cancer., 2006, 42:1591-1600; Gieseler, F., et al., Thromb. Haemost., 2008, 99: 1001-1007). The efficacy of both DOX-conjugates in combination with current MM therapeutics such as thalidomide was tested. M69-DOX by itself alone was less potent than M24-DOX. Surprisingly, inhibition of cell proliferation by M69-DOX treatment was significantly augmented by thalidomide, whereas the inhibitory activity of M24-DOX was not altered (FIGS. 6A and 6B). This enhanced inhibition by M69-DOX combined with thalidomide appeared to be synergistic, as thalidomide alone had no effect on MM cell proliferation (FIG. 6A). Therefore these studies show that thalidomide resulted in enhanced inhibition of proliferation.

Example 8 Matriptase Activation Induced by Thalidomide in MM Cells

To examine the increase in cytotoxicity that resulted with the thalidomide and M69-DOX conjugate we measured the effect of thalidomide on expression of activated matriptase. Activation of matriptase in MM cells was markedly enhanced after 24-hour treatment with 50 μM thalidomide (FIG. 8) Thalidomide is known to exert antiangeiogenic activity by interfering with the interaction between MM and bone marrow stromal cells, at least in part, through inhibition of VGEF production. While thalidomide appears to have little effect on the cell proliferation of MM cells (FIGS. 7A and 7B), its ability to activate matriptase is an important novel finding, suggesting a novel approach to exploit the response of MM cells to thalidomide treatment by targeting active matriptase-positive myeloma cells with the M69-DOX conjugate.

Example 9 Inhibition of Breast Tumor Growth by M69-DOX Targeting Active Matriptase In Vivo

To assess the efficacy of M69-DOX to suppress tumor growth in vivo, a human breast xenograft tumor model was used. NOD/SCID mice bearing breast tumors (MDA-MB468) were treated twice weekly with M69-DOX at either 20 or 10 mg/kg, as well as treated with DOX at 2 mg/kg. While the tumor sizes of the mice in the untreated control group were markedly increased at the third week, tumor growth in the mice treated with M69-DOX at either dose and treated with DOX was significantly abolished during the entire treatment course (FIG. 8). As a single mAb was attached with 7 molecules of DOX, a dose at 10 mg/kg of M69-DOX is equivalent to 0.035 mg/kg of DOX administered. These results demonstrate strong potency and efficacy of DOX conjugate targeting activated matriptase to treat breast tumors in vivo.

Reduced Weights of Tumor Masses in Mice Treated with M69-DOX

At the end of the treatment course, the tumor masses were collected from the experimental mice, and were weighed. The average weights of tumors from the groups treated with M69-DOX at either dose as well as treated with DOX were reduced to about 50% of the one from the untreated control group (FIG. 9). Significant reduction in tumor weights by M69-DOX further confirms the efficacy of site-directed delivery of DOX to tumor cells expressing activated matriptase.

Minimal Toxicity by M69-DOX Treatment

The average weights of mice treated with either M69-DOX or DOX were not markedly reduced (less than 15% loss) compared to those from untreated control group, indicating that the M69-DOX at such doses was well tolerated (FIG. 10). The dosage at 20 mg/kg of M69-DOX did not lead to noticeable toxicity, indicating that the drug dose can be escalated to reach the maximum tolerant dose.

It will be understood by those of skill in the art that numerous and various modifications can be made without departing from the scope and spirit of the present invention. Therefore, it should be understood that the various embodiments of the present invention described herein are illustrative only and not intended to limit the scope of the present invention.

All references cited herein are incorporated by reference in their entirety. 

1-17. (canceled)
 18. A method of treating a malignancy comprising cells that express matriptase, the method comprising administering to a subject in need of such a treatment a therapeutically effective amount of a composition comprising an immunoconjugate between a matriptase antibody and a cytotoxic agent.
 19. (canceled)
 20. The method of claim 18, wherein the malignancy is a matriptase-positive malignant B cell lymphoma or an epithelial carcinoma.
 21. The method of claim 20, wherein the matriptase-positive malignant B cell lymphoma is selected from the group consisting of Mantle cell lymphoma (MCL), Burkitt's lymphoma (BL), and diffuse large B-cell lymphoma (DLBL).
 22. The method of claim 20, wherein the epithelial carcinoma is selected from the group consisting of prostate, breast, brain, kidney, lung, colon, bladder, and skin tumors, and thyroid and ovary mesothelioma.
 23. The method of claim 18, wherein the malignancy is selected from the group consisting of acute lymphoblastic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), small lymphocytic lymphoma (SLL), chronic myelogenous leukemia (CML), acute monocytic leukemia (AMOL), Hodgkin's lymphomas, Non-Hodgkin's lymphomas, Mantle cell lymphoma (MCL) and multiple myeloma.
 24. The method of claim 18, wherein the malignancy is multiple myeloma.
 25. (canceled)
 26. The method of claim 18, wherein the matriptase antibody is an antigen-binding fragment.
 27. (canceled)
 28. The method of claim 18, wherein the cytotoxic agent is selected from toxins, antibiotics, and compounds comprising radioactive isotopes.
 29. The method of claim 18, wherein the cytotoxic agent is selected from doxorubicin (DOX), auristatin, calicheamicin, and ricin.
 30. The method of claim 18, wherein the cytotoxic agent is doxorubicin (DOX).
 31. The method of claim 18, wherein the malignancy is a cancer refractory to treatment with doxorubicin.
 32. The method of claim 18, wherein the cytotoxic agent is coupled to the matriptase antibody through a covalent bond.
 33. The method of claim 18, wherein the subject is a mammalian patient.
 34. The method of claim 18, wherein the subject is a human.
 35. The method of claim 18, wherein the composition further comprises a pharmaceutically acceptable carrier.
 36. The method of claim 18, comprising further administering to said subject, in combination with said immunoconjugate, a therapeutically effective amount of an immunomodulatory agent that activates matriptase.
 37. The method of claim 36, wherein the malignancy is multiple myeloma. 38-42. (canceled)
 43. The method of claim 36, wherein the immunomodulatory agent is thalidomide or a thalidomide analog.
 44. The method of claim 36, wherein the immunomodulatory agent is administered to the subject for a sufficient amount of time so that matriptase is activated prior to administration of the composition comprising the immunoconjugate.
 45. The method of claim 44, wherein: (a) the malignancy is multiple myeloma; (b) the immunoconjugate is M69-DOX; and (c) the immunomodulatory agent is thalidomide or a thalidomide analog. 46-64. (canceled) 